To perform long division, start by writing the number you want to divide. Make a division box over the number, and write the number you are dividing by the number by to the left of the box. Proceed digit by digit, dividing the outside number by the inside.

**Write the problem correctly**Consider the example 4215/5. Write the number 4215, and make a division box by drawing a line upward from a spot just to the lower left of the "4" straight up to a spot just above the upper left of the number. Turn your pen to draw at a right angle, making a horizontal line across the top of "4215." Write the "5" to the left of the vertical line.

**Begin dividing the outside number by the inside digits**Consider the example from Step 1. Calculate how many times 5 goes into 4; since 5 does not even go into 4 once, move to the right by one digit, and see how many times 5 goes into 42 without going over. Write the number "8" on top of the line above the "2," because 5 goes into 42 eight times without going over.

**Drop down, subtract and repeat**Multiply the 8 by the 5, and write "40" beneath the "42" in "4215." Write a "-" sign to the left of the "40," and subtract 42 from 40, writing "2" below that calculation. Bring the next digit ("1") down from 4215 next to the 2, making a "21." See how many times 5 goes into 21, and write the answer ("4") up on top next to the 8. Make sure you have an "84" on top of the line at this point.

**Continue to a solution**Keep bringing numbers down and repeating the process to find your solution. Finish the example problem by multiplying the "4" (from 84) by the "5", writing "20" below the "21," and subtracting to get 1. Bring down the final digit from 4215, so that the "1" is now a "15." See how many times 5 goes into 15, and write the answer (3) next to the "84," making an "843." Multiply that 3 by the 5, write the product (15) below the first 15, and subtract, yielding 0. Write the solution as 843; since the last subtraction yielded a zero, this division is exact and has no remainder.